1. Field of the Invention
The present invention generally relates to semiconductor substrate processing systems. More specifically, the invention relates to an apparatus for supporting and heating a substrate in a semiconductor substrate processing system.
2. Description of the Related Art
Accurate reproducibility of substrate processing is an important factor for improving productivity when fabricating integrated circuits. Precise control of various process parameters is required for achieving consistent results across a substrate, as well as the results that are reproducible from substrate to substrate. More particularly, uniformity of deposited material layers is one of requirements for achieving good manufacturing yield.
In a chemical vapor deposition (CVD) processing chamber, the substrate is typically disposed on a heated substrate support during processing. The substrate support generally includes embedded electric heating elements for controlling the temperature of the substrate. The substrate support may additionally include channels and grooves for a gas (e.g., helium (He), argon (Ar), and the like) to facilitate the transfer the heat between the substrate support and the substrate. Additionally, the substrate heater assembly may also comprise embedded radio-frequency (RF) electrodes for applying RF bias to the substrate during various plasma enhanced processes.
During a deposition process (e.g., chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), and the like), central and peripheral regions of the substrate are exposed to different processing conditions. Differences in the processing conditions generally result in the low uniformity for the deposited layers. For example, substrates processed on conventional heated substrate supports often allow deposition to occur right up to the substrate's edge, and may also have greater thickness of a deposited layer near the edge of the substrate relative to material deposited in the center of the substrate. Non-uniformity of the deposited layers limits yield and productivity of the deposition process, as well as overall performance of the integrated circuits. Additionally, deposited material along the edge of the substrate may be problematic to correctly positioning substrates on robotic transfer mechanisms. If the substrate is not held in a predefined position on the robotic transfer mechanism, the substrate may become damaged or dropped during transfer, or become misaligned when placed in processing equipment resulting in poor processing results.
Therefore, there is a need in the art for a substrate heater assembly for facilitating deposition of uniform material layers on the substrates without depositing material along the substrate's edge during fabrication of integrated circuits in a semiconductor substrate processing system.